1. Field of the Disclosure
The present disclosure relates to a backlight unit that improves the assembly of a liquid crystal display (LCD) device and the brightness of the backlight unit in an LCD device.
2. Description of the Related Art
Improvements in the field of LCD devices have resulted in products being manufactured that are smaller, lighter, and include more features and better performance. The cathode ray tube (CRT) had been a common display device in terms of performance and price; however, it suffers from the drawbacks of not being thin and lightweight. Accordingly, the LCD device, due to its small size, thin profile, lighter weight, and lower power consumption is considered as a suitable replacement for the CRT. LCD devices may be installed with several different kinds of data processing devices that require display devices.
Backlights that are used as light sources for LCD devices can generally be divided into two categories—edge-type and direct-type backlights. Edge-type backlights have a lamp unit installed at the side of a waveguide for guiding light. The lamp unit includes a lamp that emits light, lamp holders that insert into and protect each end of the lamp, and a lamp housing enclosing the outside of the lamp and inserting into a side of the waveguide so that it reflects the light emitted by the lamp towards the waveguide. Edge-type backlights with a lamp unit installed on the side of a waveguide may be used for smaller LCD devices, such as in laptop and desktop computers. They have favorable light uniformity, service lives, and are easy to use with a thin LCD device.
The direct-type backlight has become more common as the size of LCD devices began growing to beyond 20 inches. In the direct-type backlight method, a plurality of lamps are arranged in a single row on a lower surface of a diffuser plate to directly emit light from the front of the LCD panel. The direct-type method has an effective use of light, and is more common in large screen LCD devices that require high brightness, when compared to the edge-type method.
FIG. 1 is a perspective view of a direct-type LCD device according to the related art. Referring to FIG. 1, a direct-type LCD device includes an upper substrate with a color filter formed thereon, an LCD panel 105 coupled with a lower substrate forming a thin film transistor (TFT) and pixel electrodes, with a liquid crystal layer interposed between. A guide panel 103 is used for fixing the LCD panel 105.
The direct-type LCD device further includes a backlight unit 150 that emits light from below the LCD panel, a lower cover 120 for storing the backlight unit 150, and an upper cover 101 assembled to the lower cover 120 for protecting the LCD panel 105 and the backlight unit 150. The backlight unit 150 includes a plurality of lamps 113 that emit light, a diffuser plate 108 and light diffuser sheets 107 disposed adjacent the plurality of lamps 113, for diffusing and focusing light, and a reflective plate 117 disposed adjacent the plurality of lamps 113, to reflect light emitted towards the lower cover 120.
An inverter 123 for supplying power is attached to the rear of the lower cover 120, an inverter cover shield 124 is disposed above the inverter 123, and a cover shield 121 is provided to protect the LCD panel 105 and other components from external electrostatic discharge (ESD).
FIG. 2 is perspective view showing lamps fixed by lamp guides according to the related art. Referring to FIG. 2, the plurality of lamps 113 disposed in the backlight unit of a direct-type LCD device are fixed in groups of three by the lamp guides 109. A lamp guide 109 includes a base plate 109a on which the lamps are directly fixed by grips 109b formed a predetermined distance apart from each other. A spacer or support 109c is formed between the grips 109b to keep the diffuser plate and the light diffuser sheets located above the lamps 113 a predetermined distance away. A plurality of the above-structured lamp guides 109 may be installed through the reflective plate 117 and lower cover (not shown).
However, due to a trend of slimming direct-type LCD devices, darker regions may occur between lamps, and it may be difficult to obtain uniform brightness. Also, with the slimming of LCD devices, the lamp guides fixing the lamps can sometimes be visually seen, reducing the quality level of the display output in the eyes of a consumer.